TWI431638B - Methods of predicting a critical effective k for a nuclear reactor - Google Patents

Description

Method for predicting the critical effective k value of a nuclear reactor

This invention relates to nuclear reactors and, more particularly, to systems and methods for designing and controlling the operation of such nuclear reactors.

The statements in this section merely provide background information about the present invention and may not constitute a prior art.

In nuclear power plants, the core monitoring system provides a controlled environment for processing raw plant data into operational limit data such as maximum heat generation rates. Such systems monitor critical reactor status information, such as operational margins, axial and radial power, exposure profiles, and total core power to provide information to assess past, present, and future fuel performance. In addition, such systems are often used in accordance with the monitored data to prepare for future operation of the reactor, such as control lever sequence switching, startup, and power steering. The system can receive user input regarding planned operations and can generate models, operational features, and plans to support the planned operations. This may include simulations of planned operations based on predefined and/or calculated operational parameters and characteristics. A core simulator that calculates current, expected, and planned neutron flux, power distribution, and thermal performance as lever position, core load pattern, coolant flow, reactor pressure, and other operational and design variables function.

One of the most important published reactor parameters is the ratio of neutron gain to neutron loss, which is commonly referred to as: effective neutron multiplication factor, critical Valid k values, or critical k-feature values, each of which can be used interchangeably herein. This is the average rate of neutrons due to splitting in the core of the reactor: the ratio of the average rate of loss due to absorption and leakage. This effective k value is a constant that gives information about the current state of the chain reaction or split in the core. An effective k value of less than 1 indicates a decrease in the number of chain reactions in the current state of the reactor, and an effective k value greater than 1 indicates an increase in the number of chain reactions in the current state of the reactor. This self-sustaining steady state reactor state is referred to as the critical state of the reactor, and theoretically has an effective k value equal to 1 in the steady state. Unfortunately, this effective k value is not always equal to one due to the uncertainty associated with the reactor data and the method of calculating the quantity. The special value of this effective k value is called the critical effective k value.

During the planning phase of reactor operation, the reactor undergoes a lower than full load power reactor condition, which is referred to herein as a non-rated condition or operation, including control rod sequence exchange, startup, or power operation, from which case the reactor Engineers can prepare operational plans for reactor operators. Each non-rated condition places the reactor in a plurality of non-rated core states in which the reactor produces more or less power than full load power, for example, the effective k value is not equal to one. This reactor schedule for non-rated conditions typically includes calculating an estimate of the coolant flow rate for the target power level and lever style at each stage of operation. This process is almost the inverse of the calculation of the effective k value. These core systems support this process by providing forecasts based on pre-defined rules and past operational data. The accuracy of this calculated coolant flow rate is important to allow the target power level to be achieved as quickly as possible within the adjusted thermal limits. This poor flow rate estimate will result in: The small increase in the required flow rate of the standard power causes the time and cost of achieving full load power increase. A good estimate of the expected critical effective k value for each state point in a non-rated condition will provide a more accurate prediction of the coolant flow rate and optimum operation of the reactor.

However, since it is currently impossible to accurately predict the desired critical effective k value, the design basis effective k value or the nominal last known effective k value is typically used for flow rate calculation. Since the critical effective k value is not a constant value, it is very difficult to predict because it is a function of the complex interactions that affect all parameters of the reactor core operation. During each fuel load cycle life of the full load power rating, this critical effective k value may decrease as the cycle progresses and may vary by approximately 600 pcm (m (10 ^-3 ) percent reactivity). This change is approximately linear over a period of time and can be predicted by designing the underlying effective k value. When this critical effective k value is varied as a function of combustion, it can also vary up to 700 pcm during such non-rated conditions. This new design effective k value is calculated during the design process of refueling the core and is expected to have an accuracy of 200 pcm. However, the effective k value of this design does not address the non-rated condition where the power is below 100%.

The determination of this flow rate is sensitive to the selected critical effective k value, and thus a difference of 50 pcm in the predicted critical effective k value can result in a 2% flow rate difference. Therefore, the use of the last known value of the design effective k value or the critical effective k value of the rated condition will cause a difference of up to 25% between the calculated and actual flow rate during such non-rated power states.

Therefore, it is desirable to have a predictive method to improve the accurate calculation of the critical effective k value during non-rated conditions and conditions in order to Optimize operations while maintaining the desired margin of safety.

The inventors of the present invention have successfully designed improved systems and methods for predicting critical effective k values (k-feature values) for one or more non-rated core states during non-rated operation of the nuclear reactor, And the associated coolant flow rate through this core. In some embodiments, such nuclear reactors can be designed by providing an improved prediction of the critical effective k value in a non-rated core state, and which can be more efficient and more efficient during non-rated reactor conditions. Cost-effective operation.

According to one aspect, the present invention provides a method for determining a critical effective k value at a non-rated core state of a nuclear power plant, the method comprising: determining a lever density, core power for an off-rated core state The percentage, enthalpy reaction value, Doppler reaction value, and enthalpy reaction value are responsive to the control rod pattern, the reactor power plan including the non-rated core state, and the reference effective k value. The method includes calculating a change in the effective k value due to the non-rated core state in response to two or more parameters in the non-rated core state, the two or more parameters being selected The group consisting of: control rod density, core power percentage, enthalpy reaction value, Doppler reaction value, and enthalpy reaction value. A critical effective k value due to a non-rated core state is generated in response to a change in the effective k value due to a reference effective k value of the non-rated core state.

According to another aspect, the present invention provides a coolant for determining a nuclear reactor in a non-rated core state associated with operation of a non-rated reactor A method of flow rate, the method comprising: determining a control rod density for a non-rated core state, a percentage of core power, a change in a enthalpy reaction value, a change in a Doppler reaction value, and a change in a 氙 reaction value in response In the control lever type, the reactor power plan defines this non-rated operation including the non-rated core state, and the reference effective k value. The change in the effective k value due to the reference effective k value in the non-rated core state is calculated to respond to two or more parameters selected from the group consisting of: Changes in control rod density, percentage of core power, changes in enthalpy reaction values, changes in Doppler reaction values, changes in enthalpy reaction values, power plant types, and non-rated operation types. A critical effective k value is generated at a non-rated core state in response to the calculated change in the effective k value due to the corresponding reference effective k value. The reactor core coolant flow rate for the non-rated core state is determined in response to the critical effective k value produced.

According to still another aspect, the present invention provides a method of patterning a critical effective k value of a plurality of non-rated core states in a non-rated operation of a reactor in a nuclear power plant, the method comprising: estimating the plurality of non- Rod density, enthalpy reaction value, Doppler reaction value, and enthalpy reaction value at rated core state in response to control rod pattern, reactor power plan defining non-rated core state, and one or more references valid k value. In response to the change in the corresponding reference value and the non-rated core state, the change of the density of each control rod, the change of the 釓 reaction value, the change of the Doppler reaction value, and the change of the 氙 reaction value are calculated. . Decide on the multiple correlations in the non-rated core states affecting the neutron equilibrium in the reactor, in response to changes in core power percentage, enthalpy reaction values, and Doppler reaction Changes in values, changes in enthalpy reaction values, and changes in rod density. The change in this effective k value is determined in response to the determined correlation for each of the non-rated core states. Comparing the actual critical effective k value for one or more non-rated core states with the estimated critical effective k value for the corresponding non-rated core state, and in response to this comparison, the 氙 drive plant and the 釓 drive plant The group consisting of this power plant type is selected. It is confirmed that the at least one coefficient is confirmed for each of the plurality of coefficients associated with the determination as a function of: exposure in a non-rated core state, selected power plant type, and type for non-rated power plant operation. A subset of these correlations and coefficients is selected to be responsive to the type of power plant selected and non-rated plant operation.

According to still another aspect, the present invention provides a system for determining a critical effective k value in a nuclear reactor core in a non-rated core state, the system comprising: a computer having a processor; a memory; an input; The state is to receive the control rod pattern, the reactor power plan, reference to the effective k value, and computer executable instructions suitable for performing a method. The method executable by the computer executable instructions includes determining a lever density, a core power percentage, a 釓 reaction value, a Doppler reaction value, and a 氙 reaction value for a non-rated core state in response to a control rod-like Type, including a non-rated core state reactor power plan, and a reference effective k value; and calculating this change in the effective k value due to the reference effective k value in the non-rated core state in response to the non-rated core state Two or more parameters selected from the group consisting of: rod density, core power percentage, enthalpy reaction value, and Doppler reaction value And the reaction value. The method further includes generating a critical effective k value at a non-rated core state in response to a change in the effective k value due to a reference effective k value at the non-rated core state.

In still another aspect, the present invention provides a system for determining a critical effective k value in a nuclear reactor core in a non-rated core state, the system comprising: means for determining a control rod density of a non-rated core state , core power percentage, enthalpy reaction value, Doppler reaction value, and enthalpy reaction value in response to a control rod type, a reactor power plan including a non-rated core state, and a reference effective k value; and means for Calculating this change in the effective k value due to the reference effective k value in the non-rated core state, in response to two or more parameters in the non-rated core state, the two or more parameters are selected from The following group is composed of: control rod density, core power percentage, enthalpy reaction value, Doppler reaction value, and enthalpy reaction value. The system also includes means for generating a critical effective k value in the non-rated core state in response to a change in the effective k value due to the reference effective k value at the non-rated core state.

Other aspects of the invention are apparent in part, and a portion will be pointed out below. It will be appreciated that the various aspects of the invention can be implemented individually or in combination with one another. It is also to be understood that the invention is not intended to be limited

It should be understood that in these figures, the corresponding reference numbers show similar or Corresponding parts and features.

The following description is merely exemplary in nature and is not intended to limit the invention or the application or use of the invention.

An exemplary embodiment of a nuclear reactor is illustrated in Figure 1 with some methods and systems for patterning and predicting this critically effective k value for a non-rated core condition. Figure 1 is a cross-sectional view showing a partial cut of a boiling water type nuclear reactor pressure vessel (RPV) 10. Generally, the parts and portions described herein are well known to those skilled in the art and include various components associated with reactor control and monitoring, including reactor core 12. Heat is generated in the core 12, which includes a fuel bundle 14 of splittable material. This coolant, for example, water, circulates upward through the core 12, in some embodiments, via an injection pump 16 that provides a controlled flow of coolant through the reactor core 12. The heat generated in the core 12 can be adjusted by inserting and withdrawing a plurality of levers 18, such as the neutron absorbing material. To this extent, the control rod 18 is inserted into the fuel bundle 14, which absorbs this otherwise useful to facilitate the generation of a chain reaction of heat in the core 12. This lever 18 is controlled by a lever drive (CRD) 20 that moves the lever 18 relative to the fuel bundle 14 and, thus, controls the nuclear reaction in the core 12.

The reactor monitoring and control system 22 receives a plurality of core operational sensor signals CCs from sensors (not shown) in the core 12 and is coupled to a reactor 10 for monitoring the operation of the core 12. This may include, but is not limited to, core reactor vessel pressure, coolant temperature, coolant flow rate, reactor power, and lever position data. The reactor monitoring and control system 22 uses input data for determining, among other features, core thermal characteristics, neutron escape, neutron loss, neutron production, and actual effective k values during the operational state of each of the cores 12 ( For example, k-feature value). The reactor monitoring and control system 22 can also generate a control signal CS for controlling one or more operations or features of the reaction furnace 10. This includes a control signal CS _CR for controlling the lever driver 20 (and thus the lever 18) and a control signal CS _FR for controlling the flow rate of the liquid flowing through the core 12. This nuclear energy is generated by the reactor monitoring and control system 22, which controls: the control rod 18, and this is used to control the coolant flow of the core 12, particularly during the reactor operating period where it is less than critical, so that Adjust the power of this counter-furnace up and down. The reactor monitoring and control system 22 can also control the operation of the reactors according to a predetermined schedule that can be input to the system or prepared by the system as a function of a predetermined algorithm or model for the planned operation, It is for example: joystick switching, or power up and power down. In such plans, the adjusted reactor power level for each state and/or planned exposure over time can be presented in: reactor power plan for reactor operation, and associated lever control intend. The following items may be provided to system 22, or at least partially in accordance with one or more predefined methods performed in system 22: other parameters, factors, and correlations, including valid k values Or a change in the effective k value due to the reference to the effective k value.

In one embodiment, the method for determining the critical effective k value at a non-rated core state of a nuclear power plant includes determining for a non-rated core state: control rod density, core power percentage, enthalpy reaction value, Doppler reaction value, And the 氙 reaction value. As is known in the art, this reaction is the effect of a parameter, characteristic, or part on the reactivity or splitting of the reactor. This reactivity is the measurement of the critical offset for this reactor and is defined as r = (k _eff -1) / k _eff as described above, and k _eff is the effective k value or effective multiplication factor. This reactivity is usually expressed in units of minutes, elements, and hours. This enthalpy is therefore the effect of 釓 on the reactivity in a particular reactor power plant, and similarly to the temperature here and in the reactor, and the Doppler, for example, the Doppler temperature dependence here. The impact. Each of these values is determined as a function of the following items, or referred to herein as "responsive to" the following items: control lever type or plan; reactor power plan, which includes confirmation of one or more non-rated core states Specification; and reference to the effective k value. As explained herein, "non-rated" refers to a power condition less than 100%, and wherein the reactor is not in a critical state. The reference effective k value can be any predetermined effective k value, for example, as an example, designing a base effective k value, or finally recording a nominal effective k value.

The method includes calculating a change in one or more non-rated core states due to a valid k value of a predefined reference effective k value in response to two or more parameters in a corresponding non-rated core state. These two or more parameters include: lever density, core power percentage, enthalpy reaction value, Doppler reaction value, and enthalpy reaction value. This critical effective k value for each desired non-rated core state is generated in response to a change in the effective k value of the non-rated core state due to the reference effective k value. For example, this may be a simple reference to the effective k value by a change in some embodiments. A single adjustment, or in other embodiments, may be defined by a more complex or conversion relationship determined by the patterning of a particular reactor power plant or plant type.

Furthermore, this may include: patterning of a reactor having two or more of these parameters; establishing a correlation with one or more parameters that may affect the effective k of the reference effective k value at this non-rated core state The change in value. This may also include determining the change in the parameter or parameter correlation from its reference value, rather than merely determining the absolute value of one or more parameters. For example, this may include changes in the enthalpy reaction value, the Doppler reaction value, and/or the enthalpy reaction value, or the control rod density due to the corresponding reference value for each of the associated non-rated core states. In such embodiments, this change in the effective k value due to such predetermined reference effective k values may be derived from such individual variation values and correlations.

The patterning of the change in the critical effective k value or the effective k value of the variable may also include: confirmation and/or decision as a typical corresponding coefficient in this patterning. This may be particularly applicable to embodiments that provide an effective k value for predicting a non-rated core state by at least partially using an empirically related polynomial.

An embodiment may include a confirmation of such correlations and a summary of the coefficients or an overall set that affects all of the effects and changes in accurately predicting the effective k value. In such cases, complex relationships are determined and the application is related to considering each and every parameter. This can provide a very accurate prediction of the effective k value or the effective k value of the variable, for example, a change or difference between the predicted effective k value and the reference effective k value.

In some cases, it may be difficult to include all of the embodiments, Complex and expensive to perform. However, as will be discussed, this simplified method of using a subset of the overall set can be based on one or more factors, such as: non-rated core operational patterns (eg, cycle start, in-cycle start, power steering down power, power steering up power) , the power exchange of the pole exchange sequence, and the rising power of the pole exchange sequence, etc.), the determination of the classification or type of the intended power plant discussed herein, and/or the exposure of the non-rated core state, and is very effectively predicted at the non-rated core The effective k value in the case. Subsets of relationships and coefficients for each reactor power plant can be developed at initial system analysis and setup, or can be adjusted based on experience, measurements, or fine adjustments during plant operation.

After predicting the effective k value for one or more non-rated states, the core coolant rate for each non-rated core state can be determined or calculated as a function of: predictive effective k value, joystick-like Or for changes in lever density, and reactor power plan (eg, power percentage). As is known in the art, this lever density tends to be misnomer. Generally, as is known in the art, the lever density refers to the concentration of the lever present at the state point and is equivalent to the insertion of the lever that can be inserted into the maximum length of the control rod in the core of the reactor. The length of the part.

In some embodiments, this critical effective k can be mathematically patterned or programmed in a non-rated core state for each non-rated core state, in a computer executable instruction, by correlation of one or more parameters. Value; this one or more parameters include: power percentage, joystick density, enthalpy reaction value, enthalpy reaction value, and/or Doppler reaction value. As explained above The reaction value parameters for each nuclear reactor power plant can be determined, for example, during initial plant analysis or characterization, but adjustments can be made for fine adjustments during plant operation. Each nuclear reactor power plant has such characteristics that it is unique to the plant and cannot be easily predicted based on design or predetermined factors.

This critical effective k value can be modeled via the correlation of one or more of these parameters with each other, and via the decision on the coefficient or weighting of the one or more correlations. This critically valid k value can be modeled, for example, as a normalization factor, a different coefficient multiplied by each correlation. Examples of such correlations with more than one parameter include: power percentage multiplied by lever density, power percentage multiplied by 氙 reaction value, 氙 reaction value multiplied by lever density, power percentage multiplied by 釓 reaction value, lever density multiplied The Pupil reaction value, the lever density multiplied by the 釓 reaction value, the power percentage multiplied by the Doppler reaction value, the j power of the power percentage, the j-th power of the control rod density, and the 氙 reaction value are multiplied by the 釓 reaction value.

As explained, these coefficients can be determined for each parameter or correlation at the time the initial plant is modeled. For example, after determining various parameters and coefficients, each group correlation can be compared to the actual non-rated effective k value measured during operation of the plant. The various parameters, factors, and correlation weights can be modeled via computer to determine the coefficients such that the coefficients provide the best suitable mathematical relationship between the correlation of the plurality of non-rated states and the actual effective k values.

As explained above, the prediction of the critical effective k value may not be implemented as the absolute estimate described above, but rather due to the validity of the reference effective k value. The change in the critical change predicted in the value is implemented. In this patterning, this is modeled for each non-rated state "i" due to a change in the critical effective k value of the reference effective k value, which can be normalized by a factor multiplied by one or more correlations. These correlations are determined for each non-rated core state as described above, as a result of changes in the predetermined reference value.

By way of example, in an embodiment, this variation in the non-rated case for each reference point due to the effective k value of the rated power reference point value can be accounted for by the relationship defined by the coefficient and parameter correlation. For example, one such relationship can be illustrated by the mathematical formula illustrated in equation (1) as an example: Among them, the meaning of each parameter is: Cr: control rod density in the core P: core power percentage Gd: 釓 value Xe: 氙 value Dp: Doppler value i: the ith state point in the non-rated condition

These parameters are now provided and thus further detailed definitions are related: ith power = non-rated core state defined by non-rated operation, and having a power percentage less than 100 and an effective k value Δ(delta) not equal to 0 - For this parameter in the same non-rated state, due to the reference value and in the non-rated state parameter, and can be further defined in this relationship: ΔY ¹ = Y ¹ -Y _reference , and Y = k, Cr, Gd, Xe And Dp

a _n = a coefficient which is determined as a normalization coefficient or a weighting coefficient for the correlation. The coefficients can usually be positive or negative, as determined by the patterning and weighting associated with the particular nuclear power plant.

k = critical effective k value with the ith power Δk, which is the change in the effective k value in the non-rated core state due to the reference effective k value in the same ith unrated core state

Cr=the lever density of the i-th power ΔCr, which is the reference i-th order for the i-th power ΔCr and the j-th power due to the reference lever density Change in control rod density for rated core states

P = percentage of total power with ith power P, which is the percentage of power for the ith unrated core state and the ith power P to the jth power

Xe=the enthalpy reaction value having the ith power ΔXe, which is the change in the 氙 reaction value of the i-th non-rated core state due to the reference 氙 reaction value in the same i-th non-rated core state

Gd = 釓 reaction value with the ith power ΔGd, which is the change in the 釓 reaction value of the i-th non-rated core state due to the reference 釓 reaction value in the same ith non-rated core state

Dp = the Doppler (temperature) response value with the ith power ΔDp, which is the reference for the same i-th non-rated core state due to the reference Change in the value of the Doppler reaction value in the i-th non-rated core state

As explained above, although the patterning of critical effective k values can be provided with complete correlations and coefficients, as discussed above and as illustrated in the relationship of equation [1], in some embodiments, this non-rated The patterning of valid k values in the state can be simplified and rationalized. In some embodiments, such simplification and rationalization may be based on a non-rated operational version, and in some cases may be based on: predetermined confirmation of primary parameters, or factors affecting nuclear power plant, power plant type classification and classification.

With regard to simplified patterning and prediction for non-rated operation, when the reactor is in the startup mode, for example after refueling, these parameters and associated subsets can be used to provide a very reliable prediction of the effective k-value change. And thus predict this valid k value. This display is used for different subsets of other critical operations, including joystick manipulation or rod exchange sequences.

As illustrated, this simplified patterning and prediction can also be classified according to a predetermined power plant type. This simplified design may include confirming the nuclear power plant by type or type, which may be used later in the modeling and predicting the critical effective k value in the non-rated state. For example, some nuclear power plants can be identified as 氙-driven power plants, and the main and dominant parameters affecting the critical effective k-value prediction, and the correlation and correlation coefficients are: the control rod due to the rated power reference point, the power percentage, and the enthalpy response value. The change in density; or at least the change in the enthalpy reaction value due to the rated power reference point. In such a 氙-driven power plant, this is based on the correlation between the Doppler reaction value and the enthalpy reaction value. Accurate prediction of critically effective k-values has an unimportant effect and can be ignored during this patterning and prediction process. Rather, the enthalpy reaction value, power percentage, and joystick density may be used only in the determined correlations and coefficients; and/or adjusted to correctly and accurately predict this critically valid k value, or The change in the non-rated core state relative to the reference effective k value.

The validation or selection of this plant type can be implemented using various factors and methods due to patterning or comparison. For example, the predicted absolute value or variation due to the effective k value of the reference effective k value for one or more non-rated core states can be used, as measured for non-rated core states during subsequent actual operation of the reactor power plant. Comparison of valid k values. By comparing and patterning the various correlations and confirming their coefficients, it is possible to confirm the power plant type that best matches the specific operation of the plant. For example, the inventors identified a number of power plants that can be classified as either a 氙-driven or a 釓-driven plant based on comparison and patterning. In such cases, the operation of the plant, such as the start of a cycle start, can be simplified and rationalized by pre-determining that the plant is a sub-set of associated parameters for the plant or the drive plant.

Of course, the classification of this power plant type is also possible during the comparison of the parameters, correlations, initial modeization and analysis of the above-mentioned parameters, and the actual or measured parameters and characteristics.

This simplified patterning and prediction can also affect other methods. For example, in an exemplary embodiment, the identification and classification of this plant type as a helium reaction drive or a helium reaction drive can only be applied to one or more non-rated core operations. In the process, for example, during the initial start of the reactor, for example, at the beginning of the cycle (BOC), for example, it may not be applied to the start-up or shutdown cycle, including: joystick exchange sequence, or cycle start . Therefore, the simplified simplification and prediction of the critical effective k value provided by the nuclear power plant by means of a special predetermined power plant type may not be applied to the non-rated operation of the non-BOC.

However, in such non-rated operation of non-BOC, other simplified modeling and prediction of critical effective k values may be applied according to other plant classifications and/or according to the type of non-rated operation. This is initiated in the loop and/or power up and power down manipulations, each of which can be modeled using the above parameters and associated subsets in some processes. For example, in some embodiments, a simplified model and prediction method can be developed for power-on maneuvers, and another simplified model and prediction method can be developed for shutdown maneuvers. Simplified patterning and prediction can also be developed for other non-rated operations.

In one such simplified embodiment of the patterning and prediction of critical effective k values, a power plant can be identified as a helium driven power plant. In these exemplary embodiments, the determination of the critical effective k value or the critical effective k value of the reference effective k value relative to a particular non-rated core state at the beginning of the cycle start may be exemplified by equation (2) The relationship is outlined as an example.

In an exemplary embodiment of such a model and prediction method, coefficient selection can be applied to the relationship illustrated by equation [2], and can be performed by Explain the example in 2B].

Figure 2 illustrates the predictive variable effective k value used to previously confirm the non-rated core state at the start of the plant cycle start as a helium-driven plant. As shown in Figure 2, reference 0 is used to account for the effective k value of this predictor, and for a plurality of exposures related to the power percentage state from 40% to 100%. This predicted variable or change in the effective k value starts from a power percentage of less than 0 or minus about 40%, and increases to a power percentage of from about 42% to 65% of about 0.005. When the power is increased by approximately 65%, this predicted effective k value is reduced from 0.005 to approximately 80 power percentages of 0, and then the k value is reduced below 0 to 100 power percentages. These values for varying the effective k value can be used with reference to the effective k value to provide an improved predicted effective k value for the reactor planned operation, which is, for example, for non-rated power operation Optimum coolant flow rate for each of these non-rated states. The improved accuracy of this exemplary prediction will be explained below with reference to Figure 6.

As another exemplary embodiment, this can confirm that the nuclear reactor power plant operation of the nuclear power plant operation of the power plant, and the neutral collision factor/parameter in the core should be more accurately classified into the 釓 drive power plant type. Similar to the 氙 type power plant discussed above, this plant can be classified or identified as a 釓 power plant type, and its enthalpy response value is determined to be a major factor in addition to the lever density and power percentage. In some embodiments, as in the formula As exemplified in the relationship of [3], the 釓 type power plant can be modeled for core startup in a simplified manner, as a coefficient, a parameter, and a subset of correlations, as compared to the relationship illustrated in equation [1].

As shown, the relationship summarized by the example in [1] can be simplified to include only: normalization coefficient, change in control rod density, power percentage, 釓 reaction value change, and Doppler reaction value percentage The change, the power percentage multiplied by the control rod density, the power percentage multiplied by the 釓 reaction value, the control rod density multiplied by the Doppler reaction value, the control rod density multiplied by the 釓 reaction value And the power factor of j.

This normalization factor and the coefficient a _n for each of these correlations can be determined at the time of initial system analysis and patterning, and then used in a non-rated core case plan. Furthermore, during operation of the plant, one or more coefficients a _n may be varied or adjusted to fine tune, or based on continuous analysis to adjust the relationship and/or model, and further to predict the criticality of the non-rated core state. The value is compared to the determined actual critical effective k value in response to this operational measurement. This formula [3] of the coefficient a _n relation to the embodiment described formula [3B] in.

As explained above, the patterning and prediction of the critical effective k value in the non-rated state can also be simplified based on the classification and confirmation of the operation of the non-rated power plant. As explained above, the classification of this plant type, such as helium drive, helium drive, or Doppler drive, can provide simplified improved predictions for the start of a cycle reactor start. However, in non-activated non-rated maneuvers, in some embodiments, such plant type classifications may not be applicable.

In some embodiments that are not related to the start of the cycle and the start of the cycle start, the simplified patterning and prediction of the critical effective k value can be modeled as: a set of coefficients, parameters, and correlations. These coefficients, parameters, and correlations include: normalization factor, change in control rod density, power percentage, change in 釓 reaction value, change in Doppler reaction value, change in 氙 reaction value, power percentage multiplied by control rod density The change, the power percentage multiplied by the 氙 reaction value, the 氙 reaction value multiplied by the control rod density, the power percentage multiplied by the 釓 reaction value, the control rod density multiplied by the Doppler reaction value The change in the density of the control rod is multiplied by the change in the enthalpy reaction value, the power percentage multiplied by the change in the Doppler reaction value, the j power of the power percentage, the j-square of the change in the control rod density, and the change in the 氙 reaction value. The change in the reaction value.

However, during the power boosting maneuver in the loop, in some embodiments, this relationship can be multiplied by Doppler as described above and as shown in the exemplary relationship of equation [4] Change in response value Relevant, adjusted with different related substitutions. For power boosting manipulation, this can be replaced by a correlation between different related substitutions, ie, changes in the enthalpy response value multiplied by changes in the enthalpy reaction value. This relationship can be explained by the example of the relationship illustrated in Equation [5] for the non-starting of the cyclic power boosting operation.

This embodiment of the relationship illustrated in the formula [5] has the exemplary coefficients explained as an example in the formula [5B].

Referring now to Figure 3, this flow chart 50 illustrates an embodiment of a two-stage power plant patterning. Stage A illustrates the portion above the dashed line, which is typically implemented during initial analysis and during system and method execution. This phase A provides selection and/or confirmation of one or more plant types or classifications. In addition, the parameters including one or more reaction values are determined, and the coefficients associated with the correlation with the critical effective k-value prediction parameters are defined or determined as described above. Stage B is typically implemented during a second or subsequent non-rated core operation for predicting changes in the effective K value due to the reference effective k value, and for each non-rated state defined in subsequent non-rated core operations.

Stage A begins by receiving a joystick plan from process 52, receiving a reactor power plan from process 54, and receiving one or more reference values from process 56. Process 58 is provided to determine: 釓 reaction value, 氙 The reaction value, the Doppler reaction value, and the change in value for each of these values due to the reference value provided. This is typically implemented for a plurality of non-rated states in the reactor power plan of process 54. In process 60, a change in the effective K value due to the reference effective k value, and a plurality of correlations are determined, such as those described herein, or as an example, as in the subset of those described in the above formula [1]. The measured or actual effective k value from process 62 is received by process 64. These actual effective k values can be determined by the actual operation of the reactor power plant based on the reactor power plan and control rod plan. Process 64 compares these actual effective k values to the correlation and predicted effective k values, and typically adjusts and fine tune these coefficients based on this comparison, and selects or confirms one or more plant patterns.

Stage B receives the result of stage A from process 64 in process 66. Subsequent non-rated power plans are provided in process 68, and associated control lever configuration plans are provided in process 70, each of which is received for prediction of the desired critical effective k value. As explained above, in process 72, the operation is confirmed by the pattern and one or more of the reference values provided in process 74 are validated for operation. Such reference values may include: this reference effective k value according to the operational version or power plant type, or it may be based on the last rated effective k value, or the design basis effective k value. Depending on the plant type, the mode of operation, the parameters provided, and the correlation, a change in the effective k value due to the reference effective k value can be determined in process 76. By using the output of process 76 and the reference effective k value from process 74, the absolute value of the critically effective k value is determined in process 78 as in the general description above. Then, in process 80, it can be generated for use in subsequent non-rated power plans 68. Coolant flow rate for non-rated core conditions. Of course, as is known to those skilled in the art, other non-rated processes may also be adjusted based on predicted changes from the effective k values of process 76, or predicted effective k values from process 78.

As explained above, some of the methods described herein may provide initial analysis and plant type selection when executed in a particular nuclear power plant as illustrated by stage A illustrated in FIG. Additionally, adjustments may be made to these initial decisions during plant operation, which are typically fine adjustments to the initial patterning, including: 釓, 氙, Doppler reaction values, and an initial set of initial coefficients. In addition, new or different plant types may also be created depending on whether they are further patterned or changed in the plant over time by design or by operation. Thus, each such method or process, even if it is identified as stage A, can be considered a first step or operation, or subsequently as one or more second operations. Such second operations may include one or more non-rated plant operations defined by: a second control lever pattern; this second reactor power plan defining a second plurality of non-rated core states, A particular version of the non-rated reactor operation defining the non-rated core state of the planned exposure; a second plurality of reference effective k values; a second reference lever density; and a second reference reaction value. Each of these items can be used to predict or vary the critical effective k value for use in the non-rated core state of the second reactor power plan.

Reference is now made to Fig. 4, which illustrates an additional exemplary embodiment of the subsequent second operation. A first step is confirmed in process 82 where the 72 mode of operation is first confirmed. In this example, the first decision in process 84 is: Is this operation The beginning of the cycle start. If it is the beginning of a cycle start, the design basis valid k value is confirmed by process 86 as a reference effective k value for process 74. However, if this is not the beginning of a cycle start, the last nominal effective k value from process 88 is used as the reference effective k value in process 74.

This analysis process 66 receives a reference valid k value from process 74, receives a scheduled power plan or profile from process 68, and receives a scheduled joystick configuration from process 70. Reaction values for krypton, xenon, and Doppler are determined in process 92, and changes in these reaction values are determined at process 94. Second, if this non-rated operation is a start-up operation, then this previously confirmed plant type can be considered in process 98. If the plant is identified as a 氙 drive, then process 100 provides a decision on the critical effective k value by way of a simplified relationship as defined by equation [2] above. If the plant is identified as a 釓 drive, then process 102 provides a decision on the critical effective k value by the different simplified relationships defined by the equation [3] as an example. However, if this operation is not a power down operation for the startup operation, then process 104 provides this critical effective k value as determined by the simplified relationship defined by the equation [4] as an example. If this operation is not a power boost or power-on operation for the startup operation, then process 104 provides the critical effective k value determined by the simplified relationship defined by the equation [5] as an example.

Of course, as will be appreciated by those skilled in the art, other processes, models, or equations not described in the processes of Figures 3 and 4 are also possible and still be within the scope of the invention.

Some embodiments include: this is used to determine the non-nuclear in the core of the nuclear reactor A system for rating a critical effective k value of a core state, the system comprising: a computer having a processor; a memory; an input configured to receive a control lever type, a reactor power plan, A reference valid k value; and such computer executable instructions are suitable for performing a method. The methods executable by the computer-executable instructions include, as one or more of the methods described above, and variations of the methods described herein, as appreciated by those skilled in the art after reading the present invention.

This exemplary computer operating environment for one or more embodiments is illustrated in FIG. 5 for determining the values of the associated and predicted, predicted effective k values and the effective k values of the changes, and the decision to adjust Effective k value and coolant flow rate. The operating environment for the reactor core monitoring, planning, or forecasting system 22 can include a computer 110 including: at least one high speed processing unit (CPU) 112 and memory system 114, and at least one bus bar structure 116. An input 118 and an output 122 are connected to each other.

This input 118 and output 122 are familiar and are performed by way of example with the following connections: regional and remote user interfaces as well as controllers, remote operating systems, and operating systems. This input 118 can include, by way of example, a keyboard, a mouse, an entity converter (eg, a microphone), or a communication interface or port, and is coupled to the computer 110 via the input interface 120. This output 122 can include a display, a printer, a transducer (eg, a loudspeaker), an output communication interface, or the like, and is coupled to the computer 110 via an output interface 124. Some devices, such as network conditioners or modems, can be used as input and/or output devices.

The illustrated CPU 112 is of a familiar design and includes: an arithmetic logic unit (ALU) 126 for performing computations; a collection of such registers 128 for temporarily storing data and instructions; and a control unit 130 for The operation of control system 110. Any of a variety of processors, including those provided by at least the following companies, are equally preferred for use in CPU 112: Digital Equipment, Sun, MIPS, Motorola/Freescale, NEC, Intel, Cyrix, AMD, HP, and Nexgen. This illustrates an embodiment of the invention that is designed to be portable to an operating system on any such processing platform.

The memory system 114 typically includes high speed main memory 132 in the form of media, such as random access memory (RAM), and read only memory (ROM) semiconductor devices; and auxiliary storage in the form of long term storage media. 134, such as floppy disks, hard drives, magnetic tapes, CD-ROMs, flash memory, and the like, and other devices that use electrical, magnetic, optical, or other recording media to store data. The main memory 132 can also include video display memory for displaying images via the display device. Those skilled in the art will appreciate that the memory system 114 can include various alternative components having various storage capabilities.

As is familiar to those skilled in the art, system 22 can further include an operating system and at least one application (not shown). This operating system is a set of software that controls the operation and resource allocation of the computer system. An application is a set of software that uses the computer resources available to the operating system to implement the tasks that the user wants. Both the operating system and the application reside in the illustrated memory system 114. As familiar with this technique As will be appreciated by those skilled in the art, some of the methods, processes, and/or functions described herein can be implemented as software and can be stored on various types of computer readable media as computer executable instructions. In various embodiments of the stable radiation measurement system illustrated herein as an example, the computer system can include a robust operating program and application having computer executable instructions for implementing one or more of the processes described above. Moreover, one or more of such areas and remote user interfaces, operating systems, and remote operating systems may include, in a program of other application software having computer executable instructions, a thin client application, and Used to communicate and interact with one or more controllers as described above as an example.

The present invention is described below with reference to symbolic representations of operations performed by system 22 in accordance with the teachings of those skilled in the art. These operations are sometimes referred to as being performed by a computer. It should be understood that the operations represented by the symbols include: the CPU 112 controls the electrical signals representing the data bits, and maintains the data bits in the memory locations in the memory system 114, and other processing signals. The memory location of the saved data bit is a physical location having a specific electrical, magnetic, or optical property corresponding to the data bit. The invention can be implemented in one or more programs, including a series of instructions stored on a computer readable medium. The computer readable medium can be any of the above described with the memory system 114, or a combination of such devices.

Those skilled in the art will appreciate that some embodiments of the system or component described herein for predicting a critical effective k value or determining a coolant flow rate in a non-rated core condition may have more or fewer electrical processing system components. And still within the scope of the invention.

The process described herein and the related various embodiments, which have been tested on several different non-rated power steering, lever exchange sequences and startups, have been shown to provide significant improvements in predicting critical effective k values in non-rated states. In general, this increased accuracy of prediction is an important operating condition: the reactor is between 40% and 100% of rated power for the start-up operation of the reactor. For power handling after startup, this increased accuracy is very important for power ratings between 60% and 100%.

One or more embodiments illustrated herein show that for improved predictions of critical effective k or k eigenvalues used in a reactor core plan, the reactor core plan is used to determine coolant flow rates. Calculated non-rated condition. As demonstrated herein, some exemplary embodiments show that the error in critical k-feature value prediction is reduced to 70 to 80 pcm in most cases. This provides a significant increase in the accuracy of conventional methods and systems, which provide a prediction error of the order of 700 pcm, for example, a typical estimate of the critical effective k value (e.g., k-eigenvalue) in a non-rated condition. The error is on the order of 700pcm. Therefore, the determination of the coolant flow rate in these non-rated states and conditions is greatly improved.

Figure 6 illustrates the test results of one of the embodiments of the methods and systems described herein. Figure 6 includes a comparison of the actual monitored critical effective k values for the predicted critical effective k values for the start of a typical nuclear power plant cycle start as illustrated in Figure 2. This also shows the difference between the predicted and actual values. Some of the methods and systems described herein are not only in the preferred application area from 40 power percentages to 100 power percentages, but also in other ranges. Improvements to the critical effective k-value prediction can be provided (not shown in Figure 6). The application of the present invention can provide substantial improvements to previous methods and systems and has been shown to provide an improvement in optimized non-rated reactor operation.

The articles "a", "an", "the", and "said" are used to mean one or more elements or features. The terms "comprising", "including", "having" are intended to include and mean that there may be additional elements or features in addition to those particular.

It will be apparent to those skilled in the art that various changes may be made in the exemplary embodiments and embodiments described herein without departing from the scope of the invention. Therefore, all matter contained in the above description or illustrated in the drawings should be construed as

It should be further understood that the processes or steps described herein are not to be construed as necessarily requiring a particular order of It should also be understood that additional or alternative processes or steps may be used.

10‧‧‧Reaction furnace

12‧‧‧Reactor core

14‧‧‧Fuel cluster

16‧‧‧jet pump

18‧‧‧Control lever

20‧‧‧ rod drive

22‧‧‧Reactor monitoring and control system

110‧‧‧ computer

112‧‧‧CPU

114‧‧‧ memory system

116‧‧‧ bus bar structure

118‧‧‧Enter

120‧‧‧ interface

122‧‧‧ Output

124‧‧‧ interface

126‧‧‧Arithmetic Logic Unit

128‧‧‧ register

130‧‧‧Control unit

132‧‧‧ main memory

134‧‧‧Auxiliary storage

1 is a partially cutaway cross-sectional view of a boiling water reactor for use in some exemplary embodiments of the present invention; and FIG. 2 is a non-rated cycle operation for a percentage of power as an exposure function according to an exemplary embodiment. A schematic diagram of the predicted effective k value at the beginning; and FIG. 3 is a prediction threshold in a non-rated state according to an exemplary embodiment A flowchart of a method for valid k-values; FIG. 4 is a flow chart of another method for predicting a critical effective k value in a non-rated core state according to another exemplary embodiment; FIG. 5 is a block diagram of an exemplary computer system, This computer system can be used to perform some embodiments or parts of the system and/or method for predicting and/or patterning the critical effective k value in a non-rated core state; and Figure 6 is not rated for this cycle A diagram of the start of operation, which illustrates the actual effective k value as a comparison of the predicted non-rated effective k values as illustrated in Figure 2 of the embodiment of the present invention.

10‧‧‧Reaction furnace

12‧‧‧Reactor core

14‧‧‧Fuel cluster

16‧‧‧jet pump

18‧‧‧Control lever

20‧‧‧ rod drive

22‧‧‧Reactor monitoring and control system

Claims (10)

A method for determining a critical effective k value at a non-rated core state of a nuclear power plant, the method comprising: determining a lever density, a core power percentage, a 釓 reaction value, a degree for the off-rated core state a Pull reaction value, and a 氙 reaction value, in response to a control rod pattern, a reactor power plan including the non-rated core state, and a reference effective k value; calculating the reference effective k value from the non-rated core state at a valid k a change in value in response to two or more parameters in the non-rated core state, the parameters being selected from the group consisting of: the lever density, the core power percentage, the 釓 reaction value, the degree a Pull reaction value, and the enthalpy reaction value; and the critical effective k value generated in the non-rated core state in response to the change in the valid k value from the non-rated core state. The method of claim 1, further comprising: determining a plurality of correlations affecting the change of the reference effective k value from the non-rated core state at the effective k value, wherein the decision is made for the non-rated core state Each of the correlations includes determining one or more parameters for the non-rated core state selected from the group consisting of: a percentage of core power, a change in the enthalpy reaction value, a change in the Doppler reaction value, the 氙A change in reaction value, and a change in density of the control rod, wherein the reactor power plan includes exposure that at least partially defines the non-rated core state. The method of claim 2, further comprising: determining a change in the 釓 reaction value in the non-rated core state from a reference 釓 reaction value associated with the reference effective k value; from the reference effective k value The Doppler reaction value determines a change in the Doppler reaction value in the non-rated core state; and the reference 氙 reaction value associated with the reference effective k value determines a change in the 氙 reaction value in the non-rated core state And determining the change in density of the lever in the non-rated core state from the reference lever density associated with the reference effective k value. The method of claim 2, further comprising: confirming the coefficients for each correlation as a function of: exposure in the non-rated core state, power plant type, and non-rated power plant operation type; and confirming an empirically relevant polynomial, Included is a total set of the plurality of correlations and coefficients that affect a change in the effective k value from the non-rated core state at the effective k value, wherein the empirical correlation polynomial provides a pattern for various non-ratings for the core core The change in the effective k value of the core state. The method of claim 4, further comprising: selecting a subset of the correlations within the empirical polynomial as a function of: the non-rated core state, the predetermined power plant type, and the non-rated core state A non-rated power plant operational version, wherein calculating the effective k value change is in response to the selected subset of the selection, wherein selecting the correlated subset is responsive to a non-rated operational version, Selecting from the group consisting of: cycle start, cycle start, power steering down power, power steering up power, bar exchange sequence down power, and bar swap sequence up power, and wherein selecting a relevant subset includes generating individual patterns, For calculating the change of the reference k value from each non-rated core state at the effective k value according to the non-rated power plant operation form, and calculating the reference k value from the startup non-rated power plant operation according to the predetermined power plant form, This change in the effective k value. The method of claim 5, further comprising: measuring an effective k value during a non-rated core state; comparing the critical effective k value of the determination with the effective k value of the measurement; and driving from the 氙 drive and the 釓 drive A power plant version is selected from the group consisting of, in response to the comparison, wherein the selected subset is selected in response to the selected power plant version. The method of claim 5, wherein the nuclear power plant is a first nuclear power plant, and wherein the power plant type selected for the first nuclear power plant is executed during a core mode of the first nuclear power plant, The nuclear power plant further comprises a second nuclear power plant, wherein the power plant type selected for the second nuclear power plant is performed during the core modeling of the second nuclear power plant. The method of claim 5, wherein the non-rated plant operation, the non-rated core state, the predetermined plant type, and the associated subset of the selection are selected by the group consisting of: a. the non-rated power plant operation associated with the non-rated core state is a cycle start, and the predetermined power plant version is the 氙 drive, the associated subset of the selection being responsive to a set of parameters consisting of: the joystick density a change, a percentage of the core power, and a change in the enthalpy reaction value; b. the non-rated power plant operation associated with the non-rated core state is a cycle start, and the predetermined power plant type is a 氙 drive power plant type, the associated sub-selection The collection system is responsive to a set of parameters consisting of: a change in density of the control rod, a percentage of the core power, a change in the reaction value of the enthalpy, and a change in the Doppler reaction value; c. the non-rated operation pattern is a decrease Power steering, the associated subset of the selection is responsive to a set of parameters consisting of: a change in density of the joystick, a percentage of the core power, a change in the response value of the enthalpy, a change in the Doppler reaction value, And a change in the reaction value of the enthalpy; and d. the non-rated operational version is a rising power control, the associated subset of the selection Corresponding to the parameter set consisting of the following: the change in the control rod density, the percentage of core power, the change of the reaction of xenon value, the variation value gadolinium reaction, the reaction and the change of the Doppler value. The method of claim 1, further comprising: determining a core coolant rate for the non-rated core state in response to the generated critical effective k value, the control lever pattern, and the reactor power plan. For example, the method of claim 1 of the patent scope further includes: determining the control rod for each of the plurality of non-rated core states. Degree, the core power percentage, the enthalpy reaction value, the Doppler reaction value, the enthalpy reaction value, in response to the control rod pattern plan, the reactor power plan includes the plurality of non-rated core states, and The plurality of non-rated core states are related to one or more reference effective k values; calculating a change in the effective reference k value from each of the plurality of non-rated core states in response to the non-rated core Two or more parameters of the state, the parameters being selected from the group consisting of: the control rod density, the core power percentage, the enthalpy reaction value, the Doppler reaction value, and the enthalpy reaction value; The critical effective k value of each of the non-rated core states in response to the associated change in the effective k value for each non-rated state; and determining a core coolant rate schedule in response to being used for each non-rated core The resulting critical effective k value of the state, the control rod profile, and the reactor power plan.